Current switch driving circuit arrangements

Abstract

This current switch driving circuitry, particularly for, but not necessarily limited to, inductive device current switching, comprises a pair of output transistors constituting a driving transistor for turning ON a subsequent switching transistor and a current sinking transistor for turning OFF that switching transistor with circuit provisions for maintaining the two transistors in a low power consuming standby state. A pair of receiver circuits are arranged for applying ON and OFF logical signals individually to the two transistors by way of intermediate circuitry having current multiplying circuitry for deriving the necessary driving power with a minimum of power consumed.

The invention claimed is: 
     
       1. Current switch driving circuitry, comprising one logical signal receiving circuit having an input terminal at which ON logical signal is applied and having an output terminal,   another logical signal receiving circuit having an input terminal at which OFF logical signal is applied and having an output terminal,   an output circuit comprising   a driving transistor and a sinking transistor having the collector-emitter electron flow paths thereof connected in series and having output circuit input terminals individually connected to the base electrodes of said transistors, and   output terminals connected individually to the collector electrode and the emitter electrode of said sinking transistor,   current multiplying circuitry connected between said one logical signal receiving circuit and the base electrode of said driving transistor for actuating the latter during a desired time period,   current multiplying circuitry connected between said other logical signal receiving circuit and the base electrode of said sinking transistor for actuating the latter during another time period, and   a dissipating resistance element interposed in circuit with said collector electrode of said output driving transistor for protecting said transistors from excessive current flow in the event that both receiving circuits are at the DOWN logical level.   
     
     
       2. Current switch driving circuitry as defined in claim 1, and incorporating a switching transistor having an emitter electrode connected to one of said output terminals and a base electrode connected to the other of said output terminals, and a collector electrode, and   an inductor having one terminal connected to the emitter electrode of said switching transistor, and   circuitry for applying energizing potential between the other terminal of said inductor and said collector electrode of said switching transistor.   
     
     
       3. Current switch driving circuitry, comprising input terminals,   output terminals,   an output current sinking transistor having emitter and collector electrodes individually connected to said output terminals and having a base electrode,   an output driving transistor having an emitter electrode connected to said collector electrode of said output sinking transistor, having a collector electrode connected to a point of fixed potential and having a base electrode,   one logical signal receiver circuit for responding to ON logical signal having the input thereof connected to one of said input terminals and having an output transistor,   another logical signal receiver circuit for responding to OFF logical signal having the input thereof connected to the other of said input terminals and having an output transistor, and   current multiplying circuitry intermediate said output transistor of said other receiver circuit and said base electrode of said driving transistor,   current multiplying circuitry intermediate said output transistor of said one receiver circuit and said base electrode of said sinking transistor,   said current multiplying circuitry comprising   a plurality of transistors having like electrodes connected in parallel with the emitter electrodes connected to said base electrode of said output current transistors, the collector electrodes maintained at a fixed potential, and   a control semiconductor device connected to the corresponding receiver output transistor and to the base electrodes of said parallel connected transistors.   
     
     
       4. Current switch driving circuitry, comprising input terminals at which logical ON and logical OFF signals are applied,   output terminals at which an electric component to be driven is connected,   an output current sinking transistor having emitter and collector electrodes individually connected to said output terminals and having a base electrode,   an output driving transistor having an emitter electrode connected to said collector electrode of said output sinking transistor, having a collector electrode and a base electrode,   one current multiplying circuit having a plurality of current transistors all having emitter electrodes connected in common to said base electrode of said driving transistor, having collector electrodes connected in common to a point of fixed energizing potential and having base electrodes connected in common,   another current multiplying circuit having a control transistor and a multiple of current transistors all having emitter electrodes connected in common to said base electrode of said sinking transistor, having collector electrodes connected in common to a point of fixed energizing potential and having base electrodes connected in common,   one logical signal responsive circuit having a transistor with a base electrode coupled to the OFF input terminal, an emitter electrode connected to a point of fixed reference potential and having a collector electrode connected to said base electrode of said diode connected control transistor,   another logical signal responsive circuit having a transistor with a base electrode coupled to the ON input terminal, an emitter electrode connected to a point of fixed reference potential and having a collector electrode connected base electrode of said other control transistor, and   current sourcing circuitry connected to said collector electrode of said logical signal responsive circuits.